Question: When did the Kalmar Union have a population of 4000000?
Paraphrase: On what date did the Kalmar Union have a population of 40000000?
SPARQL (Wikidata): SELECT ?value WHERE { wd:Q62623 p:P1082 ?s . ?s ps:P1082 ?x filter(contains(?x , '4000000')) . ?s pq:P585 ?value}